[fix] allow SvelteKit to be used without bundling

[benmccann]

Banish import.meta.env from our codebase so that @sveltejs/kit works without bundling

Fixes vitest-dev/vitest#2298 and a ton of other issues I've seen like this around the ecosystem

We should probably print a big loud warning when running svelte-package if anyone tries to use import { browser, dev } from '$app/environment' and tell them to use esm-env unless they intend for their package to only be used in SvelteKit (#8033)

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@sveltejs/kit	Patch

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[dominikg]

this is neat! can we rely on browser and development conditions in exports maps to always be correctly resolved.
As long as it happens in the vite build step i think that is the case, but what about edge runtimes, do they always get output of vite or another bundler? or would there be a point where we have to rely on them to do the right thing with these conditions?

[dominikg]

using !browser for ssr a good step for compatibility 👍 otherwise node vs deno vs x would be playing catchup.

[benmccann]

what about edge runtimes, do they always get output of vite or another bundler?

Yes. If they weren't then the code currently in main wouldn't work since those environments wouldn't know how to handle import.meta.env either

[dummdidumm]

We still have __SVELTEKIT_DEV__ - do we need to keep that because it won't treeshake correctly or is the DEV equivalent from esm-env true at the wrong times?

[benmccann]

Thanks! I wasn't aware of __SVELTEKIT_DEV__. I've replaced it as well. However, doing so causes two tests to fail that I believe is due to a bug that Rich discovered in Vite 3 (vitejs/vite#9203). I fixed it for Vite 4, so after we upgrade, I'll update this branch against master and I imagine those tests should start passing. I'll mark this as a draft until then